Device for forming a zig zag wire

ABSTRACT

The invention is concerned with a device for forming a zig zag wire for a structural member such as a lattice girder. The device comprises two circular discs which are mounted coaxially and spaced apart and are coupled together and driven so that they rotate constantly and synchronously in the same direction. Each disc has distributed angularly around its periphery wire bending pins which project substantially radially from the rim of the disc. Two pivoted wire bending levers oscillated in a plane parallel to the plane tangential to the discs in which in use the lattice wire will be fed to the device. Each lever has near its end a wire bending pin and is pivoted at a location near to a different one of the discs but outside the cylindrical space defined by the two discs. The levers are driven so that they oscillate in alternation and each lever has a length such that when the lever is its extreme working position its end projects beyond the plane of the remote disc so that the lattice wire is first thrust by the wire bending pin of the one lever into the path of the wire bending pins of the remote disc to bend the wire which is subsequently bent, during the return strokes of the levers, by the pin of the other lever around a pin of the other disc. Lightweight girders with parallel upper and lower flanges joined together by a zigzag bent wire web are used in large quantities nowadays for a variety of purposes. Among the various constructions a type of girder is widely used in which the lattice wire web occupies a single plane. The flanges extend along over the peaks of the lattice wire zigzags, where the lattice wires are bent, or extend along on both sides of the peaks, symmetrically with respect to the plane of the lattice.

United States Patent [19] Schmidt et al.

[ Sept. 25, 1973 DEVICE FOR FORMING A ZIG ZAG WIRE [75] Inventors: Gerhard Schmidt; Klaus Ritter;

Hans Gott, all of Graz, Austria [73] Assignee: Firma EVG Entwicklungs-u,

Verwertungsgesellschaft m.b.H., Graz, Austria; by said Schmidt and Ritter 22 Filed: Dec. 7, 1971 21 Appl. No.: 205,547

[30] Foreign Application Priority Data Primary E.ranzinerLowell A. Larson Anorney-Ernest F. Marmorek [57] ABSTRACT The invention is concerned with a device for forming a zig zag wire for a structural member such as a lattice girder. The device comprises two circular discs which are mounted coaxially and spaced apart and are coupled together and driven so that they rotate constantly and synchronously in the same direction. Each disc has distributed angularly around its periphery wire bending pins which project substantially radially from the rim of the disc. Two pivoted wire bending levers oscillated in a plane parallel to the plane tangential to the discs in which in use the latticewire will be fed to the device. Each lever has near its end a wire bending pin and is pivoted at a location near to a different one of the discs but outside the cylindrical space defined by the two discs. The levers are driven so that they oscillate in alternation and each lever has a length such that when the lever is its extreme working position its end projects beyond the plane of the remote disc so that the lattice wire is first thrust by the wire bending pin of the one lever into the path of the wire bending pins of the remote disc to bend the wire which is subsequently bent, during the return strokes of the levers, by the pin of the other lever around a pin of the other disc.

Lightweight girders with parallel upper and lower flanges joined together by a zigzag bent wire web are used in large quantities nowadays for a variety of purposes. Among the various constructions a type of girder is widely used in which the lattice wire web occupies a single plane. The flanges extend along over the peaks of the lattice wire zigzags, where the lattice wires are bent, or extend along on both sides of the peaks, symmetrically with respect to the plane of the lattice.

5 Claims, 4 Drawing Figures PATENTED 3.760.851

saw a or 4 FIG.2

PATENTED SEPZSIQH sum 3 m4 DEVICE FOR FORMING A ZIG ZAG WIRE The invention relates to a device for forming a zigzag wire for the lattice of a girder or other structural member.

In the operation of known devices of this kind the lattice wire is bent into zigzag shape either by dies or by a toggle lever mechanism. In both cases the lattice wire advances intermittently, remaining stationary during the bending process. The entire operation is therefore intermittent, the wire being bent each time and then advanced a step.

A-further disadvantage of the known devices is that the bending tools are suitable only for producing lattice girders of specific dimensions. To convert the machine for producing lattice girders of different dimensions it is necessary to change the tools. The machine must therefore be equipped with easily exchangeable sets of tools.

The object of the invention is to provide a device which allows zigzag lattice webs to be produced from reels of wire by a continuous process. 1

In accordance with the invention such a device com prises two circular discs which are mounted coaxially and spaced apart, and which are coupled together and driven so that they rotate constantly and synchronously in the same direction, each disc having, distributed equiangularly around its periphery, wire-bending pins which project substantially radially from the rim of the disc; two pivoted wire-bending levers which oscillate in a plane parallel to the plane tangential to the discs in which in use the lattice wire will be fed tothe device, each lever having near its end a wire-bending pin and being pivoted at a location near to a different one of the discs but outside the cylindrical space defined by the two discs, the two levers being driven so that they oscillate in alternation and each lever having a length such that when the lever is in its extreme working position its end projects beyond the plane of the remote disc so that the lattice wire is first thrust by the wire-bending pin of the one lever into the path of the wire-bending pins of the remote disc to bend the wire which is subsequently bent, during the return strokes of the levers, by I the pin ofa lever is thrusting against the lattice wire the distance between the pin of that lever and the pin of the nearer disc, around which the wire is being bent, is at least approximately equal to the length of the lattice diagonal.

The device may be arranged so that it can easily be converted for producing lattice webs of different dimension without it being necessary tochange the bending tool.

For this purpose, the distance between the two discs and the distance between the pivotal axis and the wirebending pin of each lever may be continuously variable.

An example of a device constructed in accordance with the invention is illustrated in the accompanying drawings, in which:

FIG. 1 ia an axonometric view;

FIG. 2 is adiagram to illustrate the process by which the two wire-bending levers lay the lattice wire around the wire-bending pins of the two circular former discs;

FIG. 3 shows diagrammatically the mechanical drive connection between the two circular former discs and the wire-bending levers; and,

FIG. 4 illustrates diagrammatically how the device can be adjusted for producing wire lattices of different dimensions.

In FIG. 1 a lattice wire F is being fed to the device from a storage reel 10. Two flange wires G are being fed from storage reels which are not shown in the figure. The lattice wire F, coming from the storage reel 10, first of all passes through straightener devices 11, 11'. The flanges wires G also pass through straightener devices, but these are not shown in the figure.

After passing through the straightener devices 11, 11 the lattice wire passes through a'guide 12 which has the function of preventing the lattice wire from wobbling sideways. The guide 12 consists essentially of U- shaped guide bars 13 fixed to a baseplate, the lattice wire passing through the gap between the bars and the plate.

The arrangements for bending the lattice wire into zig-zag shape consist essentially of two circular former discs I4, 14, mounted coaxially and driven in rotation by a common drive. Wire-bending pins l5, 15' are positioned equiangularly around the peripheries of the former discs, which are driven by a motor not shown in the figure.

The drive motor which drives the two former discs I4, 14 also drives two oscillating wire-bending levers l6, 16, the drive to these being transmitted by a mechanism which will be described further below. The two oscillatory wire-bending levers 16, 16' are pivoted at A and A. The working ends B, B of the levers are equipped with wire-bending pins 17, 17'. The two wirebending levers 16, 16' oscillate in a plane parallel to the plane, tangential to the discs l4, 14, in which the lattice wire F is fed to the discs. Each lever oscillates on an axis situated near the discs, but outside the cylindrical surface occupied by the disc peripheries.

FIG. 2 illustrates the process of bending and laying the lattice wire. During this process the wire-bending pin of the bending lever 16, for example, follows a circular path, passing successively through the path points 0, l, 2, 3, 4. During this movement a wire-bending pin of the disc 14 follows a circular path passing successively through the path points I', 2", 3", 4", and two neighbouring wire-bending pins of the disc 14' pass successively through the path points 1", 2", 3", 4" and 1', 2', 3', 4'.

At the instant which corresponds to the path points 1, l, l", 1", the pin 17 ofthe lever 16, which is at this instant at the path point 1, is just making contact with the lattice wire F, which is already partly bent around the disc pin at the point 1" and entirely bent around the disc pin at the point 1 The lattice wire has not yet made contact with the disc pin at the point I. A constant true distance between the path points 1 and 1", 2 and 2, 3 and 3 and so on, equal to the desired lengths of the lattice diagonal, at least with close approximation, is ensured by suitably choosing the distance between each pivot axis A, A and its former disc and by suitably synchronising the oscillations of the wire-bending levers l6, 16' with the rotational speeds of the discs l4, 14.

It will be observed that the path point 4, which corresponds to the extreme position of the lever 16, is below the plane of the lowest former disc 14'. This is the disc which is furthest away from the pivot point A of the lever 16. The distance e between the path point 4 and the plane of the disc 14' is chosen in dependence on the elastic properties of the lattice wire F so that when the lever 16 moves away from the wire on its return stroke, the wire, rebounding elastically, forms the correct bend angle at the path point 4" to give the desired lattice slope angle.

As soon as the lever 16 begins moving back on its return stroke, it looses contact with the lattice wire at the bend corresponding to the path point 4. The path point 4", however, continues travelling forwards towards the path point 6". The lattice wire, restrained by the feed system, which reaches back to the storage reel 10, begins to straighten out, that is to say the bend formed at the path point 4 opens up somewhat, the wire approaching the wire-bending pin of the disc 14', which is travelling forwards between the path points 4 and 6', until finally the pin makes contact with the wire and supports it at the bend. This terminates the bending cycle of the lever 16, the lever 16 now beginning a fresh bending cycle.

In the present example the lattice wire F is supported by the wire-bending pins of the two diodes until it reaches the location on the disc peripheries where the flange wire G make contact tangentially with the discs. After the flange wires have made contact with the discs they are welded to the zigzag lattice wire, for example by means of two rotating disc electrodes 18. The completed lattice girder leaves the discs tangentially and is straightened by three straightening rollers 19. Finally the continuously produced girder is cut into sections of specified length by a cut-off device 20.

As shown in FIG. 3, the two former discs 14, 14' are driven in rotation by a driving shaft 21 which rotates in bearings 22. The driving shaft 21 is driven through a gear train by the main motor of the device, neither of these parts being shown in the drawing. Drive is transmitted through a worm 23 and worm wheel 24 to a shaft 26 which rotates in bearings 25.

Whereas the one former disc 14 is fixed to the shaft 26, the other former disc 14 is mounted on the shaft by a splined bearing 27 which allows the disc to slide along the shaft for the purpose of adjusting the gap between the discs. The disc cannot however rotate relative to the shaft, and it can be locked in position. By adjusting the distance between the discs lattice girders can be made having different specified diagonal lengths The drive for the wire-bending levers is arranged as follows. A bevel wheel 28 fixed to the driving shaft 21 drives a bevel wheel 29. A crank pin 34 of the bevel wheel 29 drives a connecting rod 30 whose other end is pivoted by a pivot pin 33 to a triangular rocker 31, which rocks on a pin 32. Rotation of the driving shaft 21 causes the triangular rocker 31 to oscillate on its pivot pin 32. This oscillation is transmitted through two driver rods 35 and 35, which are pivoted at the other two corners of the rocker, to the two wire-bending levers l6 and 16.

As shown in particular in FIG. 4, each wire-bending lever l6, 16' consists of a main lever arm 16a, l6a which oscillates on the lever axis A, A, and an adjustable lever arm 16b, l6'b, which supports at its end the wire-bending pin l7, 17.

When it is desired to manufacture a lattice girder of greater height, the circular former disc 14 is brought into the position 14". This shifts the axis A of the wirebending lever 16 into position A". In this regard it is assumed that in the present example the disc 14', mounted to slide along the shaft 26, is coupled to the axis of the lever 16' in such a way that the disc and the lever are shifted along together. This coupling is however not a necessary characteristic of the invention.

The device can if desired be arranged so that the dis-' tances between the axes A, A and the discs 14, 14' are adjustable.

The driver rods 35, 35 are long compared to the other parts of the driving mechanism for the wirebending levers 16, 16'. Consequently when the axis A is shifted to the position A" this makes hardly any change in the position of the lever 16' relative to the discs. Insofar as a change nevertheless does result, this can be compensated by adjusting the effective length of the adjustable lever arm l6b.

In the present example of the invention the wirebending pins 15, 15 are distributed over the peripheries of the discs 14, 14' in such a way that each pin on the one disc is opposite the middle point between two neighbouring pins on the other disc. The stroking of the wire-bending levers is synchronised non-variably with the rotation of the discs. Consequently lattice girders can be made with zigzags of different amplitudes, by varying the gap between the discs. The wavelength of the zigzag, on the other hand, cannot be varied.

It would of course be possible in principle to arrange the device so that, by changing the gear ratio between the stroking of the levers and the rotation of the discs, lattice girders can be produced with zigzag wavelengths which are multiples of a fundamental wavelength.

We claim:

1. Device for forming zig zag wire for a structural member such as a lattice girder, said device comprising two circular discs, means coaxially mounting said discs spaced apart, means driving said discs whereby said discs rotate constantly and synchronously in the same direction, wire bending pins equiangularly spaced around the periphery of each disc and projecting substantially radially therefrom, means feeding wire tangentially to said discs, two wire bending levers, means pivotally mounting said wire bending levers for oscillation in a plane parallel to the tangent plane to said discs in which said wire is fed thereto, a wire bending pin mounted at the end of each lever, said wire bending lever pivot means being at a location near to a different one of said discs but outside the space defined by the planes of said discs, and means driving said levers whereby said levers oscillate in alternation and at extreme working position of each of said wire bending levers, said wire bending pin at said end thereof lies beyond the plane of the remote one of said discs to carry said lattice wire into the path of said wire bending pins of said remote disc.

2. A device according to claim 1, wherein the distance between the pivotal axis of each of said wire bending levers and said nearer disc, said driving means for each lever, and said driving means for said discs are related whereby during the period in which said pin of one of said wire bending levers is thrusting against said lattice wire, the distance between said last named lever pin and said pin of said nearer disc around said wire is being bent, is substantially constant and equal to the length of a diagonal'of said lattice.

said wire bending pin being mounted at the end of said adjustable lever arm.

5. A device according to claim 1, wherein the distance between the pivotal axes of said wire bending levers and the planes of said circular discs are continuously variable. 

1. Device for forming zig zag wire for a structural member such as a lattice girder, said device comprising two circular discs, means coaxially mounting said discs spaced apart, means driving said discs whereby said discs rotate constantly and synchronously in the same direction, wire bending pins equiangularly spaced around the periphery of each disc and projecting substantially radially therefrom, means feeding wire tangentially to said discs, two wire bending levers, means pivotally mounting said wire bending levers for oscillation in a plane parallel to the tangent plane to said discs in which said wire is fed thereto, a wire bending pin mounted at the end of each lever, said wire bending lever pivot means being at a location near to a different one of said discs but outside the space defined by the planes of said discs, and means driving said levers whereby said levers oscillate in alternation and at extreme working position of each of said wire bending levers, said wire bending pin at said end thereof lies beyond the plane of the remote one of said discs to carry said lattice wire into the path of said wire bending pins of said remote disc.
 2. A device according to claim 1, wherein the distAnce between the pivotal axis of each of said wire bending levers and said nearer disc, said driving means for each lever, and said driving means for said discs are related whereby during the period in which said pin of one of said wire bending levers is thrusting against said lattice wire, the distance between said last named lever pin and said pin of said nearer disc around said wire is being bent, is substantially constant and equal to the length of a diagonal of said lattice.
 3. A device according to claim 1, wherein the distance between said two discs and the distance between the pivotal axis and said wire bending pin of each of said wire bending levers are continuously variable.
 4. A device according to claim 3, wherein each wire bending lever comprises a main pivoted arm, and an adjustable lever arm slidably mounted relatively to said main pivoted arm for movement perpendicular thereto, said wire bending pin being mounted at the end of said adjustable lever arm.
 5. A device according to claim 1, wherein the distance between the pivotal axes of said wire bending levers and the planes of said circular discs are continuously variable. 